Development of a rocking chair for use by children with spinal cord injuries

Activity-based locomotor training improves intrinsic trunk control in children with spinal cord injury (SCI). To reinforce these improvements, there is a need to develop community integration activities to allow a patient to apply the retrained nervous system at home. One activity that has been explored is rocking in a rocking chair. This paper describes the design, fabrication, and evaluation of a rocking chair for children with SCI.

The Quality Function Deployment (QFD) design process was used. Fundamental needs and features for the rocking chair were defined in a focus group with experienced therapists, and needs were then rated for importance. A House of Quality (HOQ) matrix was developed to correlate needs with design features, and a prototype design was generated. Virtual motion studies and finite element analysis (FEA) were utilized to assess the design. The chair was fabricated and physical testing was performed, including tipping and static and dynamic load assessments.

The needs identified through the QFD process were categorized into (1) safety, (2) therapeutic, (3) practical and aesthetic, and (4) data to track chair use. Features selected to meet these needs include safety stops, padding, straps, a stable base, armrests, adjustable footrest, and sensors to capture rocking data. FEA showed a factor of safety (FOS) > 5. Physical testing confirmed physical integrity, load-bearing capacity, and stability of the prototype glider rocking chair. The prototype provides a safe tool for further investigation of rocking for promotion of trunk muscle activation in children with SCI.